added some script

Okay, I think the clock is working all right now.

I didn't include the `getTime()` function, as the `setInterval()` sees that time does not exceed limit.

You can see a small demo of the clock [here](http://jsbin.com/oheteg/2/edit)

I haven't edited `index.html`, so there's just the script, and no clock.
I think @Tacho should add it at the right place, I don't want to mess up the webpage.